This invention relates to a method and apparatus for purifying a liquid. More particularly, the present invention relates to a method and apparatus suitable for simplifying the cooling equipment of an electromagnetic coil of an electromagnetic filter for separating magnetic solid particles contained in a liquid.
Proposals have been made to separate metallic particles contained in feed water to a steam generator of an atomic power plant such as the feed water to a pressure containment of a boiling water reactor power generation plant by use of an electromagnetic filter. A typical example of such proposals is illustrated in FIG. 1 of U.S. Pat. No. 3,894,391.
The electromagnetic filter has a construction in which the outer circumference of a container, into which a matrix material to be magnetized is packed, is encompassed by an electromagnetic coil. The electromagnetic coil is made of copper. When a current is caused to flow through the coil, the coil generates an induction magnetic field which magnetizes the matrix material. The coil includes therein a passage for causing cooling water to flow in order to eliminate heat generated when the current is fed.
As the cooling water of the electromagnetic coil, cooling water for an auxiliary machinery cooling system of the boiling water reactor power generation plant is used. Since the quantity of the cooling water is extremely large (approximately 17 m.sup.3 /hr for a boiling water reactor power generation plant of a 1,100 MWe class), however, the capacity of the auxiliary machinery cooling system increases remarkably, thus resulting in the remarkable increase in the size of the auxiliary machinery cooling system and eventually, in the increase in the size of the boiling water reactor power generation plant as a whole. In the auxiliary machinery cooling system, the cooling water for cooling the auxiliary machinery is cooled by a heat-exchanger using cooling water flowing through a closed loop as another circulation system and the cooling water inside the closed loop is in turn cooled by brine via another heat-exchanger.